GB2215898A - LC Displays - Google Patents
LC Displays Download PDFInfo
- Publication number
- GB2215898A GB2215898A GB8901509A GB8901509A GB2215898A GB 2215898 A GB2215898 A GB 2215898A GB 8901509 A GB8901509 A GB 8901509A GB 8901509 A GB8901509 A GB 8901509A GB 2215898 A GB2215898 A GB 2215898A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid crystal
- display element
- glass plate
- layer
- crystal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000004973 liquid crystal related substance Substances 0.000 claims description 37
- 239000011521 glass Substances 0.000 claims description 13
- 239000004990 Smectic liquid crystal Substances 0.000 claims description 8
- 238000000149 argon plasma sintering Methods 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 4
- 238000010276 construction Methods 0.000 claims description 3
- 230000010287 polarization Effects 0.000 claims description 3
- 239000000463 material Substances 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000005693 optoelectronics Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 238000005282 brightening Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000005281 excited state Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
- G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133553—Reflecting elements
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
- Mathematical Physics (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Description
DESCRIPTION
AN ACTIVE DISPLAY ELEMENT BASED ON THE
LIQUID-CRYSTAL EFFECT
The invention relates to an active display element which can be used to display information in a large variety of fields.
Display systems based on liquid-crystalline effects are well known in the pricr art. In order to recognise the information shown, external illuminating devices are used to achieve an improvement in contrast, in particular when there is low ambient light. Such illuminating devices usually provide a uniform brightening of the backgrcund with respect to area and therefore do not alter the structure or the method of operation of the liquid-crystal cell. In DE-OS 29 33 312, an ultraviolet lamp Waving a layer of luminescent material is disposed on te side of the liquid-crystal display element remote frcm the observer.
A similar solution is described in DE-OS 30 37 224, in which an electroluminescent layer is disposed on the rear side of the liquid-crystal cell. Ultraviolet radiation can, however, shorten the operating life, since it leads to photochfical reactions in the liquidcrystal layer. A further solution for increasing the contrast of the informatizn shown by way of uniform background radiation is described in DD 213 257.
Illumination is effected by light-emitting semiconductor chips, which are disopsed between the liquid-crystal cell and a wafer disposed therebeyond, which is lightscattering at the front and reflecting at the back.
When utilising electro-optical effects on the basis of interference phenomena, it is disadvantageous that exact cell optimisation, fluctuations in temperature and inhomogeneities in the layer thickness of the liquid crystal may lead to errors in colour or contrast in the information display.
DD 250 191 describes an arrangement in which light introduced laterally is reflected in dependence upon the orientation condition of the liquid-crystal molecules at the interface with the liquid crystal layer or is refracted into the layer. The disadvantages of this solution result from the use of the DSM effect. The associated high operating voltages, relatively long switching times, short operating life and limited resolution capability prevent a more wide-spread application, such as, for example, for large-area display elements. A further disadvantage in conventional electro-optical effects is that, as a result of the necessary polarizers, a considerable amount of light is lost and limited visual angle ranges for the information displayed occur.
It is an object of the present invention to provide a liquid-crystal display element for displaying information in a clearly visible manner, which element can be produced inexpensively as a result of its technologically simple structure, and hence ensures a high degree of reliability and image quality.
In accordance with the invention, an active display element based on a liquid-crystal effect, comprises a liquid-crystal cell having the following construction: glass plate - transparent electrodes, in the form of a segment, full or matrix display, - orientation layer liquid crystal - orientation layer - transparent electrodes - glass plate, and wherein the display element includes an illuminating device for laterally introducing linearly polarized light into a rear glass plate remote from an observer side of the element, the liquid crystal is a ferroelectric-smectic liquid crystal and a light-scattering layer is disposed on the side of the liquid-crystal cell facing the observer.
In order to ensure a defined state of total reflection, the liquid crystal is preferably orientated in such a way that, in the optically closed state, the longitudinal axes of the molecules are perpendicular to the polarization direction of the light radiated in.
The present invention therefore has the advantage of providing an active liquid-crystal display element, using which information can be displayed, independently of the ambient light, in high contrast and independently of the visual angle, and which is characterised by a high resolution capability, low temperature dependency and short switching times.
The invention is described further hereinafter, by way of example only, with reference to the accompanying drawing which shows the schematic structure of one embodiment of a display element in accordance with the present invention.
An active display element based on the liquidcrystal effect has the following known layer structure: a glass plate la - transparent electrodes 2a orientation layer 3 - liquid crystal 4 - orientation layer - transparent electrodes 2b - glass plate ib. In order to form a matrix, the transparnt electrodes 2a and 2b are strip-shaped and disposed perpendicularly to one another. -The display element also comprises an illuminating device 5 for laterally radiating linearly polarized light 8 into the glass plate la and is further characterised in that the liquid crystal is a ferroelectric-smectic liquid crystal 4 and a lightscattering layer 6 is disposed on the side of the liquid-crystal cell facing the observer.The ferroelectric-smectic liquid crystal 4 is orientated in such a way that, in the optically closed state, the longitudinal axes of the molecules are perpendicular to the polarization direction of the light 8 introduced.
The function of the display element is based on the principle of controllable total reflection utilising an electrically induced alteration in the refractive index.
The illuminating device 5 is set so that the polarised light falls on one side into the glass plate la and irradiates the entire interface between the orientaticn layer 3 and the liquid crystal 4. The orientation layers 3, whch are made of SiO, lead to a defined initial orientation, in which the longitudinal axes of the molecules of the liquid crystal 4 are perpendicular to the polarisation direction of the introduced light 8 (corresponds to refractive index nO). Excitation using an electrical field reorientates the liquid-crystal molecules, which results in an alteration of the refractive index to the value ne.The light introduction angle Z is selected such that, in the initial conditiion, that is given nO, it is slightly above the limiting angle of the total reflection A at the orientation layer 3/liquid crystal 4 interface, ad the light beam is reflected in total in accordance with the beam course 1. Reorientation produces ne of the liquid crystal 4. Since ne > no, the limiting angle of total reflection B at the above-mentioned interface increases, so that the light introduction angle JL is then below this limiting angle and the light beam is refracted into the liquid crystal 4 in accordance with the beam course II, and is subsequently scattered through the light-scattering layer 6 in all directions of the half-space in front of the glass plate Ib.The glass plate 1b may itself be light-scattering by virtue of increased surface roughness or other methods, as a result of which the light-scattering layer 6 may be omitted.
The thickness of the liquid-crystal layer 4 is 2 sm and is adjusted by spacers 7. In the case of large-area display elements, it is preferable to dispose the spacers 7 not only on the periphery of the component, but aso in the middle. In order to prevent these spacers 7 leading to interfering light points on the display if their dimensions are too large, lowrefracting material is used in order for total reflection to take place at these points.
For the operation mode,it would be ideal to use a ferroelectric-smectic liquid crystal 4 having a theoretical tilt angle of 450. The ferroelectricsmectic liquid crystal 4 used, which has a tilt angle of less than 450, means that, in the excited state, only part of the polarized light 8 introduced is refracted into the liquid crystal 4 and imaged on the display. The other part of the introduced polarized light 8 is reflected, in the optically closed state, at the orientation layer 3/liquid crystal 4 interface. This results only in a reduction in intensity of the information imaged; operation is not impaired. In the embodiment described, the materials listed in Table 1 were used for the various elements.
Table 1
Element Material Refractive Index
Glass plates la, b BK 7 1.52
Transparent ITO 2.00 electrodes 2a, b
Orientation layer 3 SiO 1.90
Liquid crystal 4 Ferroelectric- 1.455/1.625
smectic phase
Spacers 7 SiO2 1.44
The display element described can be used in a large variety of fields to display information by realising segment, full or matrix displays. The specific advantages of the invention are to be found above all in its active character, as a result of which the display is not dependent upon ambient light, and in its improved image quality, which is characterised by a high resolution capability, as well as in the very short switching times and in the high multiplex rate. As a result, large-area display elements are made possible.
The active ferroelectric-smectic display element is further characterised by its technologically simple construction and inexpensive production. A further substantial advantage of the display element in accordance with the invention is that no fluctuations in contrast in the information displayed occur as a result of existing inhomogeneities in layer thickness.
Claims (3)
1. An active display element based on the liquidcrystal effect, comprising a liquid-crystal cell having the following construction: glass plate - transparent electrodes, in the form of a segment, full or matrix display - orientation layer - liquid crystal orientation layer - transparent electrodes - glass plate, and wherein the display element includes an illuminating device for laterally introducing linearly polarized light into a rear glass plate remote from an observer side of the element the liquid crystal is a ferroelectric-smectic liquid crystal and a lightscattering layer is disposed on the side of the liquidcrystal cell facing the observer.
2. A display element as claimed in claim 1, wherein the ferroelectric-smectic liquid crystal is orientated in such a way that, in its optically closed state, the longitudinal axes of the molecules are perpendicular to the polarization direction of the fight introduced.
3. An active display element, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DD31288688A DD268785A1 (en) | 1988-02-08 | 1988-02-08 | ACTIVE DISPLAY ELEMENT ON A LIQUID CRYSTALLINE BASE |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8901509D0 GB8901509D0 (en) | 1989-03-15 |
| GB2215898A true GB2215898A (en) | 1989-09-27 |
Family
ID=5597019
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8901509A Withdrawn GB2215898A (en) | 1988-02-08 | 1989-01-24 | LC Displays |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH024222A (en) |
| DD (1) | DD268785A1 (en) |
| DE (1) | DE3900871A1 (en) |
| FR (1) | FR2627000A1 (en) |
| GB (1) | GB2215898A (en) |
| SE (1) | SE8900394D0 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5831698A (en) * | 1996-08-20 | 1998-11-03 | International Business Machines Corporation | Electrically variable diffuser |
| US7046425B1 (en) | 2001-12-20 | 2006-05-16 | St. Clair Intellectual Property Consultants, Inc. | Multi-stage optical switching device |
| US7177494B1 (en) | 2005-01-14 | 2007-02-13 | St. Clair Intellectual Property Consultants, Inc. | Optical control device and method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5317429A (en) * | 1990-11-28 | 1994-05-31 | Fujitsu Limited | Trilayer nematic liquid crystal optical switching device |
| CN102433990B (en) * | 2011-12-15 | 2013-12-11 | 中国一冶集团有限公司 | Reusable mould for basic foundation bolt holes of large-scale equipment |
-
1988
- 1988-02-08 DD DD31288688A patent/DD268785A1/en not_active IP Right Cessation
-
1989
- 1989-01-12 FR FR8900317A patent/FR2627000A1/en not_active Withdrawn
- 1989-01-13 DE DE19893900871 patent/DE3900871A1/en not_active Withdrawn
- 1989-01-24 GB GB8901509A patent/GB2215898A/en not_active Withdrawn
- 1989-02-06 SE SE8900394A patent/SE8900394D0/en unknown
- 1989-02-08 JP JP1027761A patent/JPH024222A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5831698A (en) * | 1996-08-20 | 1998-11-03 | International Business Machines Corporation | Electrically variable diffuser |
| US7046425B1 (en) | 2001-12-20 | 2006-05-16 | St. Clair Intellectual Property Consultants, Inc. | Multi-stage optical switching device |
| US7085037B2 (en) | 2001-12-20 | 2006-08-01 | St Clair Intellectual Property | Multi-stage optical switching device |
| US7411723B2 (en) | 2001-12-20 | 2008-08-12 | St. Clair Intellectual Property Consultants, Inc. | Multi-stage optical switching device |
| US7177494B1 (en) | 2005-01-14 | 2007-02-13 | St. Clair Intellectual Property Consultants, Inc. | Optical control device and method |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3900871A1 (en) | 1989-08-17 |
| SE8900394D0 (en) | 1989-02-06 |
| FR2627000A1 (en) | 1989-08-11 |
| DD268785A1 (en) | 1989-06-07 |
| JPH024222A (en) | 1990-01-09 |
| GB8901509D0 (en) | 1989-03-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |